Liquid calories and the failure of satiety: how good is the evidence?

Increasing rates of obesity and overweight have been attributed to the growing proportion of dietary energy that is consumed in liquid form. Liquids reportedly fail to trigger physiological satiety mechanisms so that compensation for energy consumed as beverages may be imprecise and incomplete. Sweetened beverages have come under particular scrutiny, as their consumption exceeds that of milk and fruit and vegetable juices. However, the evidence that liquids have less impact on satiety than do solid foods remains inconclusive. Some published studies have reported that liquids are less satiating than solids, whereas other studies have reported that solids are less satiating than liquids. In laboratory studies, the degree of energy compensation following pre-load ingestion was influenced by subject characteristics, pre-load volume, or the time lag between the pre-load and the next meal. Such factors appear to interact with pre-load texture in their impact on hunger and satiety and later food consumption.